The behavior of fabricated parts made from polymers results from a combination of properties attributable to both the bulk and surface properties of the polymer used. Mechanical properties are largely a function of the bulk material. Other properties can be attributed largely the result of the surface chemistry of the polymer. Such properties can include wettability, lubricity, barrier properties, chemical resistance, and UV weathering.
Polymers of carbon monoxide and ethylenically unsaturated hydrocarbons commonly referred to simply as aliphatic polyketones (hereafter, "polyketones") have been known for some time. High molecular weight alternating polyketones are of considerable interest because they exhibit a good overall set of physical and chemical properties. This class of polymers is disclosed in numerous U.S. patents assigned to Shell Oil Company exemplified by U.S. Pat. Nos. 4,880,865 and 4,818,811 which are incorporated herein by reference. These polymers are relatively high molecular weight materials having a breadth of useful properties giving them established utility as premium thermoplastics in the production of shaped articles such as gears, bearings, pipes, hose, connectors, fiber and parts for the automotive industry. The polymers display high strength, rigidity, and toughness among other favorable properties which they retain under a wide range of conditions such as temperature, moisture, and the presence of harsh chemical agents. For example, thinly molded parts comprised of polyketones have shown excellent property retention in concentrated caustic solutions. While surface discoloration can occur, bulk properties are largely retained. This makes them well suited for applications in aggressive environments such as in protective seals for the internal components of batteries.
The reactivity of polyketone groups has been used to make an array of polymeric materials with different bulk properties. For example, the introduction of other monomeric units or the modification of the polyketone backbone has resulted in the production of polymers having at least in part, polypyrrole, polyalcohols, polyester, polyfuran, polynitrile, and/or polyamine structures; each with new processing and use requirements. For example, the following patents disclose the reactions indicated: ##STR1## U.S. Pat. No. 4,929,711 discloses a similar reaction in which a peracid is used as a reactant. ##STR2## U.S. Pat. No. 3,979,373 discloses the reaction of a polyketone with phosphoric or sulfuric acid to produce a polyfuran. ##STR3## U.S. Pat. No. 2,457,279 describes the preparation of a reduced polyketone polymer through the addition of hydrazine to a polyketone. U.S. Pat. Nos. 4,616,072 and 4,687,805 describe the acidic and basic halogenation of polyketone polymers. Moreover, U.S. Pat. Nos. 5,225,523 and 5,227,465 discuss the production of low molecular weight polymers having a hybridized backbone. The modifications all relate to the bulk properties of the polymer in question. Not every polyketone presented above was, in fact, a alternating polyketone but the principle of altering the polymer backbone was seen in each.
Another means for affecting the properties of a polymer are through combination with another polymer. Frequently, this is accomplished by blending or by making multilayer composite structures. The latter are frequently utilized when one polymer can provide barrier properties while another polymer can provide mechanical and chemical resistance properties. These composites require surface adhesion between polymers which are not always mutually attractive. Thus, a mutually adhering tie-layer is often used. In the case of polyketones, amine modified polymers are particularly effective in this regard. For example, U.S. Pat. No. 5,369,170 discloses the use of an amine modified polyolefin together with a polyketone. Most aminated polymers can be combined with polyketones in this fashion. Indeed, any number of such layers are possible and can be readily accomplished through the use of multi-layer extrusion techniques well known in the art. Examples include three layer systems of polyketone/tie-layer/polyethylene and polyketone/tie-layer/polyamide-12. Five layer systems such as polyolefin/tie-layertolyketone/tie-layer/polyolefin present another example of this technology. This approach to polymer modification results in the overall property set of the composite having the average of the properties of the two (or more) polymers that are combined in layers with an improvement in some properties such as barrier or chemical resistance properties relative to the use of a single polymer. Thus, these composites find utility in automotive applications such as fuel lines, fuel tanks, and various industrial containers.
In many cases, it would be desirable to fabricate parts from alternating polyketones which exhibit different surface behaviors from those of the bulk polymer. Articles made in this manner would display the favorable property set attributable to the polymer bulk. However, other properties such as wettability, lubricity, adhesion, UV degradation resistance, barrier properties, and chemical resistance could be selectively improved to enhance to overall utility of the part so made. U.S. Pat. No. 5,405,700 discloses surface modification of polyketones with multifunctional amines which are then bonded to an epoxy resin. While this affords the polyketone with certain improvements in its surface effects, the presence of the epoxy resin also significantly affects the bulk properties of the overall composition. It would be desirable to produce materials having the bulk properties of polyketones and yet displaying improved surface properties.